Modern vehicles are often provided with an expandable airbag enclosed in an airbag module in a hub of a steering wheel in order to protect a driver in the event of a frontal impact or collision. It is further common to provide an arrangement for activation of a horn signal in the hub. The driver may activate the horn signal by applying a pressure to the airbag module. The localization in the hub is convenient, since most drivers are used to that localization and will therefore instinctively reach for that localization in case of an emergency situation. It is consequently preferred that the airbag module can flex inwards to activate the horn signal.
However, the co-localization of the airbag module and the horn arrangement makes the mounting of a steering wheel assembly a complex operation involving many manual steps. Normally the steering wheel is mounted to a steering column before the airbag module can be attached to the steering wheel. A number of cables have to be pulled through the steering wheel to the airbag. These cables are manually connected, which may be difficult due to the small space available. It is also important that the anti-vibration properties of the steering wheel are not negatively influenced. Therefore an extra cover for guiding the cables is commonly used. The conventional design thus results in additional components, such as the guiding cover, and extra steps in the manufacturing process, both of which influence the manufacturing cost of the vehicle. Further, since the airbag module is mounted to the steering wheel after the steering wheel has been mounted to the steering column, it is not possible to prepare a kit with the steering wheel plus the airbag module as a unit on a separate production line. Moreover, there is also a risk that the cables are wrongly connected or that the connection of one or more cables is forgotten.
The document U.S. Pat. No. 6,147,315 discloses a steering wheel switch assembly with several individual switches and a support housing located inside the steering wheel for the accommodation of an airbag module, by means of which at least one horn switch can be activated. Inside the steering wheel there is a stationary support plate, which supports the support housing in a spring-biased, wobbling manner. The support housing has mounted on its side facing the support plate a contact unit with connector contacts. The unit has switch guides that contact individual switches by way of connecting lines and the horn switch is located on the connecting lines.
In order to keep the manufacturing costs down, there is a desire to use as few components as possible as well as to reduce the number of steps and their complexity in the manufacturing process. There is therefore a desire to find a less complex solution than the ones existing today, a solution allowing the co-localization of the airbag module and the horn arrangement in the steering wheel hub.